Since a cycloolefin resin obtained by bulk polymerization of a polymerizable composition containing a cycloolefin monomer is excellent in mechanical characteristics, impact resistance, weather resistance and the like, a molded product obtained by the cycloolefin resin has been put to practical use in a wide range of fields. Since such cycloolefin resin itself is inflammable and flame retardance is required in some purpose of use of the molded product, addition of a flame retardant into a polymerizable composition has been proposed in recent years.
Conventionally, a halogen-containing flame retardant having a halogen atom therein has been used as the flame retardant (Japanese Patent Application Laid-Open (JP-A) No. 7-227863 or the like).
When the halogen-containing flame retardant is used, the flame retarding effect can be obtained even in a comparative small amount of addition. However, since a toxic gas is generated when waste molded product is combusted, further reduction of the amount of the addition thereof and conversion to a halogen-free flame retardant have been required.
In response to such requirements, a flame retarding technology using the halogen-free flame retardant has been reported. For Example, in JP-A No. 9-221551, disclosed is a flame retardant glass fiber reinforced polynorbornene resin molded product (cycloolefin resin molded product) obtained by bulk polymerization of a norbornene monomer in the presence of long glass fibers and red phosphorus.
Moreover, in JP-A No. 2001-234039, disclosed is a molded product (cycloolefin resin molded product) made of a polynorbornene resin containing at least one flame retardant selected from: a combination flame retardant of a phosphorus atom-containing flame retardant and a nitrogen atom-containing flame retardant; and a flame retardant having a phosphorus atom and a nitrogen atom in a molecule.
Besides, in JP-A No. 2001-64489, disclosed is a flame retardant resin composition made of (a) a metathesis polymerizable cycloolefin compound, (b) a compound insoluble in the compound described in (a), not having a halogen atom, and releasing an inert gas when being heated, and (c) a metathesis polymerization catalyst.
However, in many cases, the halogen-free flame retardant should be added in a large amount thereof to obtain the flame retarding effect, wherefore it causes reduction in mechanical properties of the molded product.